1. Field of the Invention
This invention relates to an automatic closing door hinge, an automatic closing door mechanism, and a hinge of the automatic closing door mechanism, such as a hinge for use in an opening-and-closing door including, for example, an entrance door.
2. Description of the Related Art
Conventionally, there is known a hinge and the like, for use in an opening-and-closing door including the entrance door, having automatic closing door means for automatically rotating an opening-and-closing door, upon opened, in a direction toward closing the door, and damping means for moderating an impact during closing the door. The automatic closing door means in many cases utilizes a restoration force of a coiled spring while the damping means frequently uses a hydraulic piston cylinder. Recently, there is a proposal of damping making use of air.
JP-A-9-184354 discloses a hinge structure with a damper having the following structure. Namely, in a hinge slidably coupling between cylindrical joints of leaf plates at an outer peripheral surface of a shaft, when a first leaf plate is rotated in one direction, a shaft moves axially through cam means formed between a first cylindrical joint and the shaft, to compress a spring incorporated in the cylindrical joint and expel the air within the air chamber closed by a valve device in the cylindrical joint. Furthermore, when the rotational force given to the first leaf plate is released, a restoration force of the spring moves the shaft in the other direction. By moving the shaft, the first leaf plate is rotated in the other direction through the cam means. Simultaneously, air is sucked at low speed in the air chamber through the valve device, thereby restoring the spring at low speed.
Meanwhile, JP-A-11-050738 discloses a hinge having a helical cam provided integral with a rotary shaft urged by a torsion coiled spring, to provide a piston integral with the opposed helical cam urged by a spring. The cylinder part is provided with a fine hole, to provide a damper function by a resistance of the air passing through it or by using a spring urging the cam having a piston part instead of using a torsion coiled spring, thereby providing both rotational force and damper functions.
Meanwhile, JP-A-2000-136669 discloses an automatic closing door mechanism having a pair of wing plates constituting a hinge one of which is provided with a cylinder in a circular cylindrical form, the cylinder having therein a piston to advance and retract associatively with a rotation of the other wing plate. The cylinder accommodates therein a compression coiled spring to be compressed by an advancement of the piston upon opening the door. In association with a return motion of the piston due to a restoration force of the compression coiled spring, the other wing plate is rotated in a direction toward closing the door. Furthermore, impact is damped upon closing the door, by the action of air cushioning within the cylinder due to a return movement of the piston.
The above automatic closing door mechanism having a damping function utilizing air-cushioning action is simple in structure and to be manufactured easily at low cost, enabling size reduction and space saving. Furthermore, there is a merit of no possibility of oil leak possibly staining the surrounding.